I have checked the manual but there is not entry like searching transitoin states in PSI4.
Yes, one can do transition-state searches, http://psicode.org/psi4manual/master/optking.html#transition-states-reaction-paths-and-constrained-optimizations . Sorry the manual looks odd at the moment, but the content is there.
Thanks very much Lori! This is exactly what I need.
Chester